Tm010 mode resonator, oscillator and transceiver

ABSTRACT

To provide a TM010 mode resonator device, an oscillator device, and a transmission and reception device having radiation of an electromagnetic field suppressed and a high Q.  
     A TM010 mode resonator  2  having circular resonator electrodes  2 A and  2 B, opposite to each other, formed on the top surface  1 A and bottom surface  1 B of a dielectric substrate  1 , respectively, is formed. Furthermore, in the dielectric substrate  1 , a plurality of through holes  3  having no electrode on the inner wall surface  3 A thereof are formed along the circular resonator electrodes  2 A and  2 B, and an open-circuited end is formed by these through holes  3 . Thus, an electromagnetic field generated in the dielectric substrate  1  is reflected totally at the boundary between the through holes and the air, and radiation of the electromagnetic field can be suppressed.

TECHNICAL FIELD

The present invention relates to a TM010 mode resonator device foroscillating a high-frequency electromagnetic wave of microwaves,millimeter waves, etc., an oscillator device, and a transmission andreception device.

BACKGROUND ART

In general, a TM010 mode resonator device having circular electrodes,opposite to each other, formed on both surfaces of a dielectricsubstrate is known for use in transmission and reception devices, suchas communication devices and radar devices. (see Patent Document 1, forexample).

Patent Document: Japanese Unexamined Patent application PublicationNo.10-98316

In such a TM010 mode oscillator device according to the prior art, whencompared with a TM01 mode resonator device in which a groundingelectrode is formed on the substantially whole bottom surface of thedielectric substrate, since the thickness of the dielectric substratecan be increased about double the thickness of a substrate where thecoupling to an electromagnetic field of a TM0 mode as a surface wavemode does not occur, about twice as large a conductor Q (Qc) and no loadQ (Qo) can be obtained and a low loss filter becomes possible.

Now, in the above TM010 mode resonator device of the prior art, when Q(quality factor) is heightened by increasing the thickness of thedielectric substrate, an electromagnetic field in the dielectricsubstrate is coupled to a TM0 mode and distributed as a radiation mode.Because of this, the energy concentration in the dielectric substrate islowered and, since Q is inversely deteriorated by the radiation loss,there is a problem in that the effect of increasing the conductor Q (Qc)by increasing the thickness is offset.

DISCLOSURE OF INVENTION

The present invention has been made in consideration of the aboveproblem of the prior art, and it is an object of the present inventionto provide a TM010 mode resonator device, an oscillator device, and atransmission and reception device suppressing radiation of anelectromagnetic field and having a high Q.

In order to solve the above problem, according to the present inventionof claim 1, a TM010 mode resonator device comprises a dielectricsubstrate; electrodes formed on both surfaces of the dielectricsubstrate, at least one of the electrodes being a circular electrode;and a plurality of through holes passing through the dielectricsubstrate and formed around the circular electrode in the dielectricsubstrate, the inside of each through hole having no electrode as noelectrode-formed portion. In the TM010 mode resonator device, anopen-circuited end for improving confinement of an electromagnetic fieldis provided around the circular electrode by using the plurality ofthrough holes.

Under such a construction, an electromagnetic field is generated byresonance in the portion corresponding to the circular electrode in thedielectric substrate and the electromagnetic field can be reflectedtotally by using the open-circuited end. Accordingly, it is able toimprove no load Q by suppressing radiation of the electromagnetic fieldand the energy confinement can be heightened.

Furthermore, in the present invention, a plurality of through holespassing through the dielectric substrate are formed around the circularelectrode in the dielectric substrate, the inside of each through holehaving no electrode is made no electrode-formed portion, and theopen-circuited end is formed by the plurality of through holes.

Thus, since air is filled in the through holes, the electromagneticfield can be reflected totally at the boundary between the inner wallsurface of the through holes and the air and the generatedelectromagnetic field can be confined in the portion corresponding tothe circular electrode in the dielectric substrate.

In the present invention, it is desirable that, when the wavelength of aresonance frequency in the dielectric substrate is represented by λg,the space between neighboring through holes be λg/4 or less. Thus, it isable to prevent an electromagnetic field from leaking from betweenneighboring through holes and the energy confinement can be heightened.

Furthermore, in the present invention, a TM010 mode resonator devicecomprises a dielectric substrate; electrodes formed on both surfaces ofthe dielectric substrate, at least one of the electrodes being acircular electrode; and a plurality of strip electrodes disposed so asto radially extend around the circular electrodes formed on bothsurfaces or the circular electrode formed on one surface of thedielectric substrate so as to have a space between the circularelectrodes or the circular electrode and the plurality of stripelectrodes.

In this case, when the wavelength of a resonance frequency of thedielectric substrate is represented by λg, by setting the lengths of thestrip electrodes at λg/4, for example, the tip portion (side of theoutermost end) of each strip electrode can be short-circuited in apseudo way. Alternatively, by setting the length of the strip electrodesat λg/2, for example, the tip side of each strip electrode can beopen-circuited in a pseudo way. At this time, since the circularelectrode is enclosed by a plurality of radially disposed stripelectrodes, it is able to make an electromagnetic field generated in theportion corresponding to the circular electrode in the dielectricsubstrate reflected totally at the tip side of the strip electrodes as ashort-circuited end or an open-circuited end, and the energy confinementcan be heightened. As a result, even if the thickness of the dielectricsubstrate is increased, since radiation of an electromagnetic field canbe suppressed, it is able to simultaneously improve the conductor Q andthe radiation Q and to effectively heighten no load Q.

In the present invention it is desirable that, when the wavelength of aresonance frequency is represented by λg, the radially extending lengthof the strip electrodes be λg/4 and the strip electrodes be rectangularin shape.

Thus, the tip side (side of the outermost end) of each strip electrodecan be short-circuited in a pseudo way. Accordingly, an electromagneticfield generated in the portion corresponding to the circular electrodein the dielectric substrate can be reflected totally at the tip side ofthe strip electrodes as a short-circuited end and the energy confinementcan be heightened.

In the present invention, it is desirable that the space betweenneighboring strip electrodes be set to be λg/4 or less. Thus, it is ableto prevent an electromagnetic field from leaking from betweenneighboring strip electrodes and to heighten the energy confinement.

Furthermore, an oscillator device may be constituted by using a TM010mode resonator according to the present invention and also atransmission and reception device, such as a radar device andcommunication device, by using an oscillator device according to thepresent invention.

When an oscillator device and a transmission and reception device areconstituted by using a TM010 mode resonator device according to thepresent invention, the structure of the oscillator device, etc., can besimplified and also the manufacturing cost of the whole communicationdevice can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing a TM010 mode resonator deviceaccording to a first embodiment.

FIG. 2 is a top view showing the TM010 mode resonator device in FIG. 1.

FIG. 3 is a sectional view of the TM010 mode resonator device taken online III-III of FIG. 2.

FIG. 4 is a perspective view showing a TM010 mode resonator deviceaccording to a second embodiment.

FIG. 5 is a top view showing the TM010 mode resonator device in FIG. 4.

FIG. 6 is an enlarged top view of an essential part, a strip electrodeat location a in FIG. 5.

FIG. 7 is a perspective view showing the TM010 mode resonator deviceaccording to a second embodiment housed in a cavity.

FIG. 8 is characteristic lines showing the relation between the spaceheight from the TM010 mode resonator device in FIG. 7 to the cavity andthe coefficient of variation of the resonance frequency.

FIG. 9 is an enlarged top view of an essential part, at the sameposition as that in FIG. 6, a strip electrode of a first modifiedexample.

FIG. 10 is an enlarged top view of an essential part, at the sameposition as that in FIG. 6, a strip electrode of a second modifiedexample.

FIG. 11 is an enlarged top view of an essential part, at the sameposition as that in FIG. 6, a strip electrode of a third modifiedexample.

FIG. 12 is an enlarged top view of an essential part, at the sameposition as that in FIG. 6, a strip electrode of a fourth modifiedexample.

FIG. 13 is an enlarged top view of an essential part, at the sameposition as that in FIG. 6, a strip electrode of a fifth modifiedexample.

FIG. 14 is an enlarged top view of an essential part, at the sameposition as that in FIG. 6, a strip electrode of a sixth modifiedexample.

FIG. 15 is an enlarged top view of an essential part, at the sameposition as that in FIG. 6, a strip electrode of a seventh modifiedexample.

FIG. 16 is a top view showing a TM010 mode resonator device according toa third embodiment.

FIG. 17 is an enlarged top view of an essential part, a strip electrodeat location b in FIG. 16.

FIG. 18 is an enlarged top view of an essential part, at the sameposition as that in FIG. 17, a strip electrode of an eighth modifiedexample.

FIG. 19 is an enlarged top view of an essential part, at the sameposition as that in FIG. 17, a strip electrode of a ninth modifiedexample.

FIG. 20 is a top view showing an oscillator device according to a fourthembodiment.

FIG. 21 is an electric circuit diagram of the oscillator device in FIG.20.

FIG. 22 is a block diagram showing a communication device according to afifth embodiment.

REFERENCE NUMERALS

-   1, and 11 dielectric substrates-   2, and 12 TM010 mode resonators-   2A, 2B, 12A, and 12B resonator electrodes (circular electrodes)-   3 through hole-   13, 14, 21-27, and 31-33 strip electrodes-   56 TM010 mode resonator device-   61 communication device (transmission and reception device)-   76 oscillator device

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an oscillator device and a communication device accordingto embodiments of the present invention are described in detail withreference to the accompanying drawings.

First, FIGS. 1 to 3 show a TM010 mode resonator device according to afirst embodiment. In the drawings, reference numeral 1 represents adielectric substrate constituting the main body of a TM010 moderesonator device and the dielectric substrate 1 is formed by using aceramic material having a dielectric constant εr of about 24 (εr≈24),for example. Furthermore, the dielectric substrate 1 is made of asubstantially square flat plate, for example, and constitutes a smallpiece of plate having an area which is a size larger than resonatorelectrodes 2A and 2B to be described later.

Reference numeral 2 represents a TM010 mode resonator formed in themiddle of the dielectric substrate 1 and the TM010 mode resonator 2contains resonator electrodes 2A and 2B made of circular electrodeswhich are located in the middle of the dielectric substrate 1 and formedon the top surface 1A and bottom surface 1B, respectively. Furthermore,the resonator electrodes 2A and 2B are formed by using a conductive thinfilm of a metal material, etc., and disposed at opposite locations so asto form a substantially cylindrical form, and then, the diameter D isset to be a value according to the wavelength λg of the resonancefrequency in the dielectric substrate 1 (D=λg, for example).

Then, an electric field E extending in the thickness direction of thedielectric substrate 1 between the resonator electrodes 2A and 2B isgenerated in the dielectric substrate 1 and simultaneously a magneticfield H which is concentric around the central position of the resonatorelectrodes 2A and 2B is generated (see FIGS. 2 and 3). Furthermore, inthe resonator electrodes 2A and 2B, a current I flows along theradiation direction between the central position and the outerperiphery.

Reference numeral 3 represents a plurality (twelve, for example) ofthrough holes formed along the periphery of the resonator electrodes 2Aand 2B so as to pass through the dielectric substrate 1, and the innerwall surface 3A (inner portion) of each through hole is noelectrode-formed portion where no electrode is contained. Furthermore,the space P0 (pitch) between neighboring through holes 3 is set to be ¼or less of the wavelength λg of the resonance frequency in thedielectric substrate 1 (P0≦λg/4). Then, the plurality of through holes 3are disposed so as to enclose the resonator electrodes 2A and 2B and thethrough holes 3 form an open-circuited end as a whole.

The TM010 mode resonator device of the present embodiment has theabove-described structure and, when the TM010 mode resonator 2 operates,electric fields E in opposite directions to each other are formed at thecentral position of the resonator electrodes 2A and 2B and at the outerperipheral position, and a magnetic field concentric around the centralposition of the resonator electrodes 2A and 2B is formed. Thus, theTM010 mode resonator 2 resonates at a frequency in which the diameter Dof the resonator electrodes 2A and 2B is one wavelength.

However, the TM010 mode itself is generally a radiation mode, and thereare many cases in which such a characteristic is utilized inapplications such as antennas, etc. However, when the resonator deviceis used as a TM010 mode resonator 2, there is a problem in that, sincethe radiation is large, the radiation loss deteriorates and no load Q(Qo) is also worsened.

In contrast to that, in the present embodiment, since the plurality ofthrough holes where the electrode of the inner wall surface 3A isomitted is formed along the periphery of the resonator electrodes 2A and2B of the dielectric substrate 1, the total reflection of anelectromagnetic field generated between the resonator electrodes 2A and2B can be performed at the boundary between the inner wall surface 3A ofthe through holes 3 and the air. As a result, it is able to suppress theradiation of an electromagnetic field and heighten no load Q (Qo), andalso it is able to improve the energy confinement.

Furthermore, since the space P0 between neighboring through holes 3 isset to be ¼ or less of the wavelength λg of the resonance frequency, itis able to present an electromagnetic field from leaking from betweenneighboring through holes 3 and to increase the confinement of theelectromagnetic field.

Next, a TM010 mode resonator device according to a second embodiment isshown in FIGS. 4 to 6. The present embodiment is characterized in that aplurality of strip electrodes enclosing the resonator electrodes aredisposed so as to radially extend on both surfaces of the dielectricsubstrate.

Reference numeral 11 represents a dielectric substrate substantially thesame as the dielectric substrate 1 of the first embodiment, and thedielectric substrate 11 is formed so as to be a substantially squareflat plate by using a ceramic material having a dielectric constant εrof 25 (εr=25), for example.

Reference numeral 12 represents a TM010 mode resonator formed in themiddle of the dielectric substrate 11, and, substantially in the sameway as the TM010 mode resonator 2 of the first embodiment, the TM010mode resonator 12 contains resonator electrodes 12A and 12B made ofcircular electrodes which are located in the middle of the dielectricsubstrate 11 and formed on the top surface 11A and bottom surface 11B,respectively. Furthermore, the resonator electrodes 12A and 12B areformed by using a conductive thin film and disposed at oppositelocations to each other, and then, the diameter D is set to be a valueaccording to the wavelength λg of the resonance frequency in thedielectric substrate 11 (D=λg, for example).

Then, the central position and external peripheral position of theresonator electrodes 12A and 12B are made open-circuited in a pseudo wayand electric fields in opposite direction to each other are generated atthese portions. Furthermore, a magnetic field which is concentric aroundthe central position of the resonator electrodes 2A and 2B is generatedbetween the resonator electrodes 12A and 12B. Thus, a frequency in whichthe diameter D of the resonator electrodes 12A and 12B is one wavelengthresonates with the TM010 mode resonator 12.

Reference numerals 13 and 14 represent pluralities of strip electrodesenclosing the resonator electrodes 12A and 12B formed on the top surface11A and bottom surface 11B of the dielectric substrate 11, respectively,and the plurality (24, for example) of strip electrodes 13 which areradially extend are disposed around the resonator electrodes 12A so asto have a fixed minute space of a dimension d (d≈50 μm, for example)between the strip electrodes 13 and the resonator electrodes 12A. In thesame way, the plurality of strip electrodes 14 which are radially extendare disposed around the resonator electrode 12B so as to have a fixedspace of a dimension d between the strip electrodes 14 and the resonatorelectrode 12B.

Furthermore, each of the strip electrodes 13 and 14 is substantiallyrectangular and the radially extending length L of the electrodes is setto be a value of about ¼ of the wavelength λg pf the resonance frequency(L=λg/4). Thus, since the tip side (side of the outermost end) of thestrip electrodes 13 and 14 is short-circuited in a pseudo way, and anannular ring-shaped short-circuited end in which the TM010 moderesonator 12 is enclosed by the pluralities of strip electrodes 13 and14 can be formed.

Moreover, on the tip side of the strip electrodes 13, the space P1(pitch) between neighboring strip electrodes 13 separated in thecircumferential direction is set to be ¼ or less of the wavelength λg ofthe resonance frequency (P1≦λg/4). In the same way, also on the tip sideof the strip electrodes 14, the space P1 (pitch) between neighboringstrip electrodes 14 is set to be ¼ or less of the wavelength (P1≦λg/4).

Moreover, the strip electrodes 13 and 14 may be disposed at positionsopposite to each other or positions displaced in the circumferentialdirection so as to sandwich the dielectric substrate 11. Furthermore,the numbers of the strip electrodes 13 and 14 may be the same ordifferent from each other.

The TM010 mode resonator device of the present embodiment has theabove-described structure and the basic operation of the TM010 moderesonator 12 is not different from the TM010 mode resonator 2 of thefirst embodiment.

Here, in order to improve no load Q (Qo) of the TM010 mode resonator 12,there is a method of increasing the thickness of the dielectricsubstrate 11 in addition to a method of decreasing the radiation loss.This is because the conductor Q (Qc) is represented by the ratio of thethickness t of the dielectric substrate 11 to the skin depth δ (Qc=t/δ).For example, when the thickness t of the dielectric substrate 11 is 0.6mm (t=0.6 mm) and the skin depth a is 0.6 μm (δ=0.6 μm), the conductor Q(Qc) becomes 1000 (Qc=1000). In this way, when the thickness t of thedielectric substrate 11 increases, it is able to improve the conductor Q(Qc), but, in contrast with this, there is a tendency to increase theradiation loss.

As a result, even if the dielectric substrate 11 is formed like a chip,for example, and the end face is made open-circuited, when the thicknessof the dielectric substrate 11 is increased, there is a problem in thatthe energy confinement is worsened because of radiation.

Contrary to this, in the present embodiment, since pluralities of stripelectrodes 13 and 14 radially extending so as to enclose the resonatorelectrodes 12A and 12B are formed on the top surface 11A and bottomsurface 11B of the dielectric substrate 11, the tip sides of the stripelectrodes 13 and 14 is short-circuited in a pseudo way and the electricfield can be concentrated between the resonator electrodes 12A and 12B.Because of this, in the present embodiment, a magnetic field energy canbe confined and the radiation of an electromagnetic field can besuppressed.

In order to confirm the effect of suppression of radiation by such stripelectrodes 13 and 14, the cases in which a resonator device having stripelectrodes 13 and 14 and a resonator device not having strip electrodes13 and 14 are contained inside a cavity 15 of a substantially squarebox-like space, respectively, were assumed (see FIG. 7). In eachresonator device, the coefficient of variation Δf/f0 of a resonancefrequency when the space height of the upper portion of the cavity 15(side of the top surface 11A of the dielectric substrate 11) was changedwas calculated by using a three-dimensional electromagnetic fieldsimulation. The result is shown in FIG. 8.

Moreover, the result in FIG. 8 was calculated under the assumption thatthe resonance frequency f0 is 38 GHz (f0=38 GHz), the dielectricconstant of the dielectric substrate 11 εr is 25 (εr=25), the thicknessof the dielectric substrate 11 is 0.6 mm (t=0.6 mm), the length L0 ofone side of the substantially square dielectric substrate 11 is 2.5 mm(L0=2.5 mm), the diameter D of the resonator electrodes 12A and 12B is1.6 mm (D=1.6 mm), the length L of the strip electrodes 13 and 14 is0.23 mm (L=0.23 mm), the width W of the strip electrodes 13 and 14 is0.1 mm (W=0.1 mm), the number of the strip electrodes 13 and 14 is 24,the space d between the resonator electrodes 12A and 12B and the stripelectrodes 13 and 14 is 50 μm (d=50 μm), and the length L1 of one sideof the substantially square cavity 15 is 3 mm (L1=3 mm).

Furthermore, the dielectric substrate 11 is disposed in the middle ofthe cavity 15 so as to be floated. Practically, the dielectric substrate11 is disposed on a support made of a low dielectric material so as notto affect the resonance characteristics of the TM010 mode resonator 12.

From the result in FIG. 8, when strip electrodes 13 and 14 are formed asin the present embodiment, when compared with the case in which thestrip electrodes 13 and 14 are eliminated, it is understood that thevariation of the resonance frequency F0 is small even if the height h ofthe space of the cavity 15 is changed. That is, since the radiation ofan electromagnetic field in the case where the strip electrodes 13 and14 are formed is smaller than in the case where the strip electrodes areeliminated, it is understood that the effect of the cavity 15 is littleand it was able to confirm the effect of suppression of radiation by thestrip electrodes 13 and 14.

In this way, in the present embodiment, since pluralities of stripelectrodes 13 and 14 radially extending so as to enclose the resonatorelectrodes 12A and 12B are formed on the top surface 11A and bottomsurface 11B of the dielectric substrate 11, the tip side of each of thestrip electrodes 13 and 14 can be short-circuited in a pseudo way bysetting the length L of the strip electrodes 13 and 14 at one fourth ofthe wavelength λg of the resonance frequency. At this time, since theresonator electrodes 12A and 12B are enclosed by the pluralities ofstrip electrodes 13 and 14 disposed so as to radially extend, the totalreflection of an electromagnetic field generated between the resonatorelectrodes 12A and 12B can be performed on the short-circuited tip sideof the strip electrodes 13 and 14.

As a result, even if the thickness of the dielectric substrate 11 isincreased, since the radiation of an electromagnetic field between theresonator electrodes 12A and 12B can be suppressed, both conductor Q(Qc) and radiation Q (Qr) can be simultaneously improved and it is ableto heighten no load Q (Qo) of the TM010 mode resonator 12.

Furthermore, since the space P1 between neighboring strip electrodes 13and 14 is set to be ¼ or less of the wavelength λg of the resonancefrequency (P1≦λg/4), it is able to prevent an electromagnetic field fromleaking from between neighboring strip electrodes 13 and 14 and toincrease the energy confinement.

Moreover, in the second embodiment, the length L of strip electrodes 13and 14 is set to be ¼ of the wavelength of the resonance frequency andthe tip side of strip electrodes 13 and 14 is open-circuited in a pseudoway. However, the present invention is not limited to this, and, forexample, the length of strip electrodes is set to be one half of thewavelength λg of the resonance frequency and the tip side of stripelectrodes may be open-circuited in a pseudo way. Furthermore, thelength of strip electrodes are not limited to these and the tip side maybe short-circuited or open-circuited in a pseudo way.

Furthermore, in the second embodiment, strip electrodes 13 and 14 of asubstantially rectangular shape are used. However, the present inventionis not limited to these, and, for example, as in first to seventhmodified examples shown in FIGS. 9 to 15, substantially triangular stripelectrodes 21, substantially rhombic strip electrodes 22, substantiallytrapezoidal strip electrodes 23, substantially hexagonal stripelectrodes 24, substantially pentagonal strip electrodes 25,substantially long-hole strip electrodes 26 both ends of which arecircular, substantially oval strip electrodes 27, etc., may be used.

Next, FIGS. 16 and 17 show a TM010 mode resonator device according to athird embodiment and the present embodiment is characterized in thatstrip electrodes are of a stepped impedance type in which the impedancechanges in a stepwise manner in the middle of the length direction ofthe strip electrodes. Moreover, in the present embodiment, the samereference numerals are given the same components as in the secondembodiment and their description is omitted.

Reference numeral 31 represents strip electrodes on the top surface 11Aand bottom surface 11B of the dielectric substrate 11 so as to enclosethe resonator electrodes 12A and 12B. Substantially in the same way asin the strip electrodes 13 and 14 of the second embodiment, a fixedspace having a minute space d is formed between the strip electrodes 31and the resonator electrodes 12A and 12B, and a plurality, 24, forexample, of strip electrodes 31 are disposed so as to radially extend.

Furthermore, the strip electrodes 31 in which the middle in the lengthdirection is widened and both ends are narrowed are substantiallycross-shaped. In the strip electrodes 31, the impedance in the lengthdirection changes in a step-wise manner and the tip side (side of theoutermost end) of the strip electrodes 31 is short-circuited in a pseudoway. Thus, substantially in the same way as in the strip electrodes 13and 14 of the second embodiment, in a plurality of strip electrodes 31,a ring-shaped short-circuited end enclosing the TM010 mode resonator 12is formed. Moreover, at the tip side of the strip electrodes 31, thespace P1 (pitch) between neighboring strip electrodes 31, which areseparated from each other in the circumferential direction, is set to be¼ or less of the wavelength of the resonance frequency (P1≦λg/4).

Moreover, the strip electrodes 31 may be disposed at opposite positionsto each other or at positions displaced in the circumferential directionso as to sandwich the dielectric substrate 11. Furthermore, the numbersof strip electrodes 31 may be the same or different from each other.

The TM010 mode resonator device of the present embodiment has the aboveconstruction and the basic operation of the TM010 mode resonator 12 isnot different from that of the TM010 mode resonator 12 according to thesecond embodiment.

However, in the present embodiment, since the substantially cross-shapedstrip electrodes 31 in which the impedance changes in a step-wise mannerin the middle of the length direction are used, when compared with thecase where substantially square strip electrodes 13 and 14 are used asin the second embodiment, for example, the dimension in the lengthdirection can be reduced. Accordingly, the whole resonator device can bereduced in size.

Moreover, in the third embodiment, substantially cross-shaped stripelectrodes 31 are used as a stepped impedance type. However, the presentinvention is not limited to this, and, for example, as in the eighthmodified example shown in FIG. 18, substantially dumbbell-shaped stripelectrodes 32 in which both ends in the length direction are widened andthe middle is narrowed may be used. Furthermore, as in the ninthmodified example shown in FIG. 19, for example, substantially T-shapedstrip electrodes 33 in which one end in the length direction is widenedand the other end is narrowed may be used.

Furthermore, in the second and third embodiments, the strip electrodes13, 14, 21 to 27, and 31 to 33 are formed on both of the top surface 11Aand bottom surface 11B of the dielectric substrate 11. However, thepresent invention is not limited these, and, for example, stripelectrodes may be formed only on either of the top surface and bottomsurface of a dielectric substrate. In this case, it is considered thatthe effect of radiation suppression of an electromagnetic field isreduced by half.

Moreover, in the first to third embodiments, both of the resonatorelectrodes 2A, 2B, 12A, and 12B of the TM010 mode resonators 2 and 12are formed so as to be in a circular shape, but if either of them is ina circular shape, it is sufficient.

Furthermore, in the first to third embodiments, the dielectricsubstrates 1 and 11 of the TM010 mode resonator devices aresquare-shaped, but they may be of another shape such as of a circularshape, oval shape, etc., for example.

Next, FIGS. 20 and 21 show a fourth embodiment of the present invention,and the present embodiment is characterized in that an oscillator deviceis constituted by using a TM010 mode resonator device. Moreover, in thepresent embodiment, the same reference numerals are given the samecomponents as in the first embodiment and their description is omitted.

Reference numeral 41 represents an oscillation circuit substrate made ofa dielectric material, and the oscillation circuit substrate 41 isformed by using a ceramic material, resin material, etc., having a lowerdielectric constant compared with the dielectric substrate 1 of theTM010 mode resonator 56, for example, and is of a substantially squareflat plate.

Reference numeral 42 represents an oscillation circuit portion formed onthe surface of the oscillation circuit substrate 41, and the oscillationcircuit portion 42 contains a field-effect transistor 43 (hereinafter,referred to as an FET 43), a microstrip line 44, a bias circuit 45, etc.Then, a power-supply voltage is supplied to the oscillation circuitportion 42 through a power supply terminal 41A, a signal of a fixedoscillation frequency set by the TM010 mode resonator 2, and the signalis output through an output terminal 41B.

Here, the gate terminal G of the FET 43 is connected to the baseterminal side of the microstrip line 44. Furthermore, the sourceterminal S of the FET 43 is connected to the bias circuit 45 on thesource side and to an inductive stub 46 as an inductor for controllingthe feedback frequency.

On the other hand, the drain terminal D of the FET 43 is connected tothe power supply terminal 41 A through a filter circuit 47 made up of aninductive stub 47A and a capacitor 47B, and a bias resistor 48, andconnected to the output terminal 41B through a coupled line 49 forcutting off a DC component. Furthermore, a capacitor 50 for surgeelimination is connected to the power supply terminal 41A.

Moreover, a terminating resistor 51 is connected to the tip side of themicrostrip line 44; the microstrip line 44 has a branch circuitbranching substantially in a T shape in the middle of the lengthdirection, and one side of the branch circuit as an excitation electrode44A for exciting the TM010 mode resonator 2 extends toward thedielectric substrate 1.

Reference numeral 52 represents a frequency control circuit formed onthe surface of the oscillation circuit substrate 41, and the frequencycontrol circuit 52 is disposed on the opposite side of the oscillationcircuit 42 so as to sandwich the dielectric substrate 1. Furthermore,the frequency control circuit 52 is basically constituted by amicrostrip line 53 one end of which is disposed in the vicinity of theTM010 mode resonator 2 and a variable capacitance diode 54 (varactordiode) as a modulation element connected to the other end of themicrostrip line 53.

Here, the cathode terminal of the variable capacitance diode 54 isconnected to the microstrip line 53 and the anode terminal is grounded.Furthermore, a control input terminal 41C is connected to the cathodeterminal of the variable capacitance diode 54 through an inductive stub55 as a choke coil. Moreover, the tip side of the microstrip line 53constitutes an excitation electrode 53A for exciting the TM010 moderesonator 2.

Then, the frequency control circuit 52 makes the capacitance of thevariable capacitance diode 54 change in accordance with the controlvoltage applied to the control input terminal 41C to control theoscillation frequency (resonance frequency).

Reference numeral 56 represents the TM010 mode resonator deviceaccording to the first embodiment formed between the oscillation circuit42 and the frequency control circuit 52, and the dielectric substrate 1of the TM010 mode resonator device 56 is mounted on the top surface ofthe oscillation circuit substrate 41 between the oscillation circuit 42and the frequency control circuit 52.

Furthermore, the resonator electrode 2B formed on the bottom surface ofthe dielectric substrate 1 out of the resonator electrodes 2A and 2B ofthe TM010 mode resonator is grounded through the land (not illustrated)formed on the top surface of the oscillation circuit substrate 41, etc.Then, the TM010 mode resonator 2 is connected to the oscillation circuit42 and the frequency control circuit 52 through the excitationelectrodes 44A and 53A of the microstrip lines 44 and 53.

The oscillator device of the present embodiment has the aboveconstruction, and next, the operation is described.

When the drive voltage is applied to the power supply terminal 41A, asignal in accordance with the resonance frequency of the TM010 moderesonator 2 is input to the gate terminal G of the FET 43. Thus, sincethe oscillation circuit 42 and the TM010 mode resonator device 56constitute a band reflection type oscillation circuit, the FET 43amplifies the signal in accordance with the resonance frequency of theTM010 mode resonator 2 and outputs the amplified signal to the outsidethrough the output terminal 41B.

Furthermore, since the frequency control circuit 52 having the variablecapacitance diode 54 is connected to the TM010 mode resonator device 56,it is able to make the resonance frequency of the TM010 mode resonator 2variable in accordance with the value of the control voltage applied tothe control input terminal 41C. In this way, the whole oscillator devicefunctions as a voltage control oscillator (VCO).

Thus, in the present embodiment, since the oscillator device isconstituted by using the TM010 mode resonator device 56 according to thefirst embodiment, it is able to suppress radiation of theelectromagnetic field of the TM010 mode resonator 2 to the outside, anda cavity enclosing the TM010 mode resonator device 56 can be eliminated,for example. Because of this, the oscillator device can be made lower inheight and simplified, and, as a result, the manufacturing cost can bereduced.

Moreover, in the fourth embodiment, although the TM010 mode resonatordevice of the first embodiment is used as the TM010 mode resonatordevice 56, also the TM010 mode resonator device of the second or thirdembodiment may be used.

Next, FIG. 22 shows a fifth embodiment of the present invention, and thepresent embodiment is characterized in that a communication device as atransmission and reception device is constituted by using an oscillationdevice having a TM010 mode resonator device of the present invention.

Reference numeral 61 represents a communication device according to thepresent embodiment, and the communication device 61 is constituted by asignal processing circuit 62, a high-frequency module for outputting orinputting a high-frequency signal which is connected to the signalprocessing circuit 62, and an antenna 65 for transmitting or receivingthe high-frequency signal through an antenna sharing device 64(duplexer) connected to the high-frequency module 63.

Then, in the high-frequency module 63, the transmission side isconstituted by a bandpass filter 66, an amplifier 67, a mixer 68, abandpass filter 69, and a power amplifier 70 connected between theoutput side of the signal processing circuit 62 and the antenna sharingdevice 64, and the reception side is constituted by a bandpass filter71, a low-noise amplifier 72, a mixer 73, a bandpass filter 74, and anamplifier 75 connected to the antenna sharing device 64 and the inputside of the signal processing circuit 62. Then, the oscillator device 76using a TM010 mode resonator device of the present invention as in thefourth embodiment, for example, is connected to the mixers 68 and 73.

The communication device of the present embodiment has the aboveconstruction, and, next, the operation is described.

First, in transmission of a signal, after unnecessary signals in anintermediate signal (IF signal) output from the signal processingcircuit 62 have been eliminated in the bandpass filter 66, theintermediate frequency signal is amplified by the amplifier 67 and theninput to the mixer 68. At this time, the mixer 68 as an up-convertergenerates a high-frequency signal (RF signal) by mixing the intermediatefrequency signal and a carrier wave from the oscillator device 76. Then,after unnecessary signals in the high-frequency signal output from themixer 68 has been eliminated in the bandpass filter 69, thehigh-frequency signal is amplified by the power amplifier 70 andtransmitted from the antenna 65 through the antenna sharing device 64.

On the other hand, in reception of a signal, a high-frequency signalreceived from the antenna 65 is input to the bandpass filter 71 throughthe antenna sharing device 64. In this way, after unnecessary signals inthe high-frequency signal have been removed in the bandpass filter 71,the high-frequency signal is amplified by the low-noise amplifier 72 andinput to the mixer 73. At this time, the mixer 73 as a down-convertergenerates an intermediate frequency signal by mixing the high-frequencysignal and a carrier wave from the oscillator device 76. Then,unnecessary signals in the intermediate frequency signal output from themixer 73 are eliminated in the bandpass filter 74, and the intermediatefrequency signal is amplified by the amplifier 75 and then input to thesignal processing circuit 62.

Thus, according to the present embodiment, since a communication deviceis constituted by using the oscillator device 76 having a TM010 moderesonator device of the present invention in which radiation issuppressed, the construction of the oscillator device 76 can besimplified and the manufacturing cost of the total communication devicecan be reduced.

Moreover, in the fifth embodiment, although the case in which anoscillator device 76 using a TM010 mode resonator device of the presentinvention is applied to the communication device 61 is described as anexample, the oscillation device 76 may be applied to a radar device,etc.

1. A TM010 mode resonator device comprising: a dielectric substrate;electrodes formed on opposite surfaces of the dielectric substrate, atleast one of the electrodes being a circular electrode; and a pluralityof through holes extending through the dielectric substrate and arrangedaround the circular electrode on the dielectric substrate, wherein aninside of each through hole does not have an electrode and, wherein theplurality of through holes are arranged around the circular electrode toform an open-circuited end for improving confinement of anelectromagnetic field.
 2. The TM010 mode resonator device as claimed inclaim 1, wherein, when a wavelength of a resonance frequency in thedielectric substrate is represented by λg, a space between neighboringthrough holes is λg/4 or less.
 3. A TM010 mode resonator devicecomprising: a dielectric substrate; electrodes formed on oppositesurfaces of the dielectric substrate, at least one of the electrodesbeing a circular electrode; and a plurality of strip electrodes disposedso as to radially extend around the at least one circular electrodeformed on the dielectric substrate such that there is a space betweencircular electrodes or the at least one circular electrode and theplurality of strip electrodes.
 4. The TM010 mode resonator device asclaimed in claim 3, wherein, when a wavelength of a resonance frequencyin the dielectric substrate is represented by λg, a length of theradially extending strip electrode is λg/4 and the strip electrodes arerectangular in shape.
 5. The TM010 mode resonator device as claimed inclaim 3, wherein a space between neighboring strip electrodes is λg/4 orless.
 6. An oscillator device comprising: a TM010 mode resonator deviceas claimed in claim
 1. 7. A transmission and reception devicecomprising: a TM010 mode resonator device as claimed in claim
 1. 8.TheTM010 mode resonator device as claimed in claim 4, wherein a spacebetween neighboring strip electrodes is λg/4 or less.
 9. An oscillatordevice comprising: a TM010 mode resonator device as claimed in claim 3.10. A transmission and reception device comprising: a TM010 moderesonator device as claimed in claim 3.